JPH0576713B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a capstan servo circuit for a magnetic recording/reproducing device, and in particular to a capstan servo circuit for controlling a capstan motor by switching between a mode in which tracking volume adjustment is necessary and a mode in which it is not necessary. The present invention relates to a device for driving and controlling a motor.

BACKGROUND ART FIG. 8 shows a block system diagram of an example of a capstan servo circuit of a conventional magnetic recording/reproducing apparatus.
The recording mode will be explained. The video signal A (FIG. 9A) that entered the terminal 1 is separated from the vertical synchronization signal B (FIG. 9B) by the vertical synchronization signal separation circuit 2.
A 30 Hz oscillation circuit (counter) 3 driven by counting the clock from the crystal oscillator 18 generates a signal H (C in the figure). Here, the threshold values C ₄ , C ₅ ,
C ₆ , C ₇ (C ₄ < C ₅ < C ₆ < C ₇ ) are set, and the 30Hz signal D (D in the same figure) is extracted in synchronization with the vertical synchronization signal B by the threshold C ₅ , and the waveform It is supplied to the shaping circuit 4 and becomes the signal E (E in the same figure), which is then sent to the recording amplifier 5.
The data is supplied to the control head 6 via the magnetic tape and recorded on the magnetic tape.

On the other hand, in the drum servo system, a trigger pulse is extracted by the threshold value C ₆ of the oscillation circuit 3, converted into a sample pulse by the sample pulse generation circuit 8 (F in the figure), and supplied to the phase comparator circuit 10. Drum PG pulse from drum motor 13 (G in the same figure)
is taken out, is made into a signal high (H in the same figure) and a signal low (I in the same figure) by the monomultis 14 and 15, and is made into a signal N (J in the figure) by the flip-flop 16, and then sent to the trapezoidal wave generating circuit 17. This is called a trapezoidal wave signal (K in the same figure).

The phase comparison circuit 10 compares the phases of the trapezoidal wave signal and the sample pulse, and the phase comparison error signal is supplied to the drum motor 13 via a reduction filter (LPF) 11 and a motor drive amplifier (MDA) 12. 13 is driven and controlled.

On the other hand, in the capstan servo system, the clock of the crystal oscillator 18 is sent to the capstan reference oscillation circuit 19 and the trapezoidal wave shaping circuit 20 as a signal (O in the figure).
The trapezoidal wave generating circuit 21 generates a trapezoidal wave signal (P in the figure), and the signal is supplied to the phase comparator circuit 22. Capstan from capstan motor 25
The FG pulse is converted into a sample pulse wave (M in the figure) via an amplifier 26, a frequency dividing circuit 27, and a sample pulse generation circuit 28.

The phase comparison circuit 22 compares the phases of the trapezoidal wave signal and the sample pulse wave, and the phase comparison error signal is supplied to the capstan motor 25 via a reduction filter (LPF) 23 and a motor drive amplifier (MDA) 24. Drive control of the capstan motor 25.

By the way, during reproduction, image quality may deteriorate due to deviations in the X value when replacing magnetic tapes, variations in linearity of tape patterns, and the like. Therefore, the user operates the tracking volume VR provided in the tracking monomulti 29 to adjust the video head so that it performs the best tracking. In this case, as long as self-recording and playback is performed, the same tracking pattern as during recording is traced at the center position of the tracking volume VR during playback, but if there are variations in the tracking volume VR, even in the case of self-recording and playback. Sometimes it is not possible to trace the same track pattern at the center position, and in such cases the recorded pattern is played back using the Fix mode described later.

In FIG. 8, in the reproduction mode, the tracking monomulti 29 (delay time T ₁ =16.6 msec) generates a signal (N in the figure) from the signal obtained by the threshold value C ₇ of the oscillation circuit 3; A trigger pulse is extracted by the threshold value _C4 of the oscillation circuit 3. here,
When there is no need to adjust the tracking deviation (in the case of self-recording and playback, when the tracking volume VR is at the center position and the recording is played back as recorded), switch SW ₂ is connected to the Fix terminal side, while adjusting the tracking deviation. When adjustment is required, switch SW ₂ is connected to the terminal side. This means that an L level control signal is supplied to switch SW 2 when the tracking volume is at the mechanical center position, and an H level control signal is supplied to switch SW ₂ when the tracking volume VR is deviated from the mechanical center position. According to
Each can be switched to Fix. A trigger pulse based on the signal mode (mode) or the threshold value _C4 is converted into a signal Y (O in the figure) by the trapezoidal wave shaping circuit 20, and is converted into a trapezoidal wave signal T (P in the figure) by the trapezoidal wave generating circuit 21.

At this time, the tracking deviation can be adjusted using the tracking volume VR of the tracking monomulti 29, and the signal force can be given a tracking variable range τ ₁ . Also, between the thresholds C ₄ and C ₇
There is a difference of 16.7 msec, and the delay time _T1 of the tracking monomulti 29 is 16.6 msec, so the trapezoidal wave signal obtained from the signal force from the threshold _C7 in the mode and the trapezoidal wave signal obtained from the threshold _C4 in the fix mode. The trapezoidal wave signal will have the same phase relationship with respect to the phase of the oscillation circuit 3.

The phase of the trapezoidal wave signal from the trapezoidal wave generating circuit 21 and the sample pulse generated from the signal obtained through the amplifier 30 are compared with the reproduction control pulse from the control head 6 (L in the same figure). The capstan motor 25 is driven and controlled using the phase comparison error signal thus obtained.

Problems to be Solved by the Invention The conventional circuit described above transmits signals and control pulses necessary for the Fix mode and the mode to the oscillation circuit 3.
The number of bit patterns must be obtained from three threshold values C ₄ , C ₇ , and C ₅ , which results in a problem that the circuit cannot be constructed easily and inexpensively.

According to the present invention, signals and control pulses necessary for the Fix mode and modes can be obtained from two or one threshold value set in the oscillation circuit, and the circuit can be easily configured with fewer bit patterns than conventional circuits. An object of the present invention is to provide a capstan servo circuit for a magnetic recording/reproducing device.

Means to Solve the Problems In Figure 1, the oscillation circuit (counter) 31 counts signals with a higher frequency than the vertical synchronization signal separated from the video signal, and is reset to the vertical synchronization signal during recording, and is reset to the vertical synchronization signal during playback. The flip-flop 32, which is a means of self-running and extracting 60Hz oscillation output, reverses the polarity when the count value of the counter reaches the threshold value.
Means to output 30Hz signal, AND gate circuit 3
3 is a means for obtaining a 60Hz signal having a timing different from that of the 30Hz signal and performing logic with the output signal of the 30Hz output means;
The output of the logic means is configured to be supplied to a circuit for obtaining control pulses and also to a tracking adjustment circuit.

Operation The oscillation circuit 31 takes out the 60Hz oscillation output, and the flip-flop 32 inverts the polarity when the count value of the counter reaches, for example, the first threshold value _C1 .
A 60 Hz signal is output _{, and the AND gate 33 outputs a 60 Hz signal when the count value of the counter reaches a second threshold C 3 which} is larger than the first threshold C 1.
An AND operation is performed with the output signal of the Hz output circuit, and the ANDed output is supplied to a circuit for obtaining control pulses, and is also supplied to a tracking adjustment circuit.

Embodiment FIG. 1 shows a block system diagram of a first embodiment of the circuit of the present invention. In the figure, the same components as in FIG. 8 are given the same numbers, and the same signals are given the same symbols. Therefore, the explanation will be omitted.

Here, the so-called double gap method applied to the circuit of the present invention will be explained. In a double-gap type magnetic recording/reproducing device, video heads SP1 and SP2 are used in the standard play mode (SP) (2-hour mode) during recording and normal playback, as shown in FIGS. 5A and B. In mode (EP) (6-hour mode), video heads EP1 and EP2 are used. video head
EP2 and SP1 are attached, for example, 2H apart from each other on the circumference of the rotating drum.

Here, for still playback in SP mode, video heads EP2 and SP2 with the same azimuth angle are used as shown in FIGS. 6A and 7G and H, and for still playback in EP mode, video heads EP2 and SP2 are used as shown in FIGS. As shown in Figures I and J, video heads EP1 and SP1 with the same azimuth angle are used. Note that FIG. 7G and I show video head switching modes, and FIG. 7H and J show still FM levels. By doing this, field stills have a high playback FM level during stills and have less blur compared to frame stills.
Can be used in both SP mode and EP mode.

On the other hand, for the recording control pulse, an X value is specified to ensure compatibility of the magnetic tape. The pulse is to be recorded. As a result, in the double gap method, the time charts shown in Figure 7 A, B, C, and D are obtained in SP mode, and the time charts shown in Figure 7 A, B, and D are obtained in EP mode.
This is the time chart for B, E, and F. Note that A in the same figure is a video signal, B in the same figure is a drum PG pulse, C and E in the same figure are channel switching modes, and D and F in the same figure are recording control pulses.

Therefore, if the relative height H between the video heads SP and EP in Figure 5A is close to normal, then the heights in Figure 7B and
As shown in D and F, SP for drum PG pulse
The recording timing of the recording control pulse is set to 1 field (16.6 msec) in mode and EP mode.
It is necessary to shift it.

Now, the recording mode will be explained with reference to FIG. The vertical synchronizing signal RO (FIG. 2B) is converted into a signal c (FIG. 2C) by a 60 Hz oscillation circuit (counter) 31. The oscillation circuit 31 has threshold values C ₁ , C ₂ , C ₃ (C ₁ <C ₂
<C ₃ ) is set, and a 30 Hz signal d (D in the same figure) is taken out from the flip-flop 32 by the threshold C ₁ , while a 60 Hz signal f (F in the same figure) is taken out by the threshold C ₃ .

In the SP mode, the signal d and the signal f are ANDed by the AND gate 33 and the signal g (G in the same figure)
The control pulse generating circuit 34 generates a recording control pulse h (H in the figure). EP
In the mode, the output signal d of the flip-flop 32 is inverted in polarity by the inverter 35, and the signal f is ANDed with the signal i (I in the figure), and the control pulse generating circuit 34 The recording control pulse j (J in the figure) is defined as the recording control pulse j (J in the figure).

On the other hand, in the drum servo system, the oscillation circuit 31
A trigger pulse k (K in the same figure) is taken out by the threshold value C ₂ of , and is supplied to the flip-flop 36. The output signal d of the flip-flop 32 is converted into a reset pulse e (E in the figure) by the reset pulse generation circuit 37, and is supplied to the flip-flop 36. The signal l (L in the figure) is taken out from the flip-flop 36, and is sent to the trapezoidal wave generation circuit. At 9, trapezoidal wave signal m (M in the same figure)
It is said that

The drum PG pulse n (N in the same figure) from the drum motor 13 is sent to the monomultis 14 and 15 as signals o and 15, respectively.
p (O, P in the same figure), and the flip-flop 16
The sample pulse generating circuit 17 generates a signal q (Q in the figure), and the sample pulse generating circuit 17 generates a sample pulse r (R in the figure).

On the other hand, the capstan servo system is the same as the conventional circuit shown in FIG. 8 during recording. In playback mode, if tracking deviation adjustment is not required, connect switch SW ₂ to the Fix terminal. or,
When adjustment of tracking deviation is required, switch SW ₂ is connected to the terminal side and a signal s (S in the figure) is obtained from the tracking monomulti 40. In this case, the switch SW ₁ is connected to the terminal SP in the Fix mode and to the terminal EP in the SP mode, and is connected to the terminal EP in the Fix mode and to the terminal SP in the EP mode.

In this way, in the playback mode, as shown in FIG. 2, the signal s has a tracking variable range τ ₂
can have. Also, similar to the conventional circuit, the trapezoidal wave signal obtained from the signal g to the signal s in the fix mode and the trapezoidal wave signal obtained from the signal g in the fix mode have the same positional relationship with respect to the phase of the flip-flop 32.

In the present invention, signals and control pulses necessary for the Fix mode and the mode can be obtained using two threshold values C ₁ and C ₃ in the oscillation circuit 31, and the number of bit patterns can be reduced compared to the conventional circuit shown in FIG. .

FIG. 3 shows a block system diagram of a second embodiment of the circuit of the present invention, in which the same components as those in FIG. omitted. Thresholds C ₁ , C ₂ , C ₉ , C ₃ (C ₁ <C ₂ <C ₉ <C ₃ ) are set in the 60Hz oscillation circuit 41, and the flip-flop 43 is set according to the threshold _C9.
A drum FF signal q' (FIG. 4G) is extracted from.

Also, the signal y from the monomulti ₄₂ is determined by the threshold value C2.
(H in the figure) is taken out and made into a signal l' (I in the figure) by the flip-flop 36, and made into a signal m' (J in the figure) by the trapezoidal wave generating circuit 9. drum motor 13
The drum PG pulse n (K in the same figure) from is converted into a sample pulse r' (L in the same figure) in the waveform shaping circuit 44 and the sample pulse generation circuit 17, and its phase is compared with the signal m' in the phase comparator circuit 10. .

Note that instead of obtaining the signal f from the threshold _C3 , the threshold
The signal f may be obtained by obtaining a signal delayed from C ₁ to the timing of the threshold C ₃ , and in this case, only the threshold C ₁ is sufficient.

Effects of the Invention According to the circuit of the present invention, signals and control pulses necessary for the Fix mode and modes can be obtained from two or one threshold value set in the counter, and the number of bit patterns is also reduced compared to the conventional circuit. It has the advantage that the circuit can be constructed easily and at low cost.

[Brief explanation of the drawing]

1 and 2 are block system diagrams and their signal waveform diagrams, respectively, of a first embodiment of the circuit of the present invention, and FIGS. 3 and 4 are block system diagrams and their signal waveform diagrams, respectively, of a second embodiment of the circuit of the present invention. Signal waveform diagram, Figure 5 is a configuration diagram of a video head of a double gap type magnetic recording/reproducing device, Figure 6 is its track pattern, Figure 7 is a diagram showing the relationship between its control pulse and head switching, and Figure 8. 9 are a block system diagram and a signal waveform diagram of an example of a conventional circuit, respectively. DESCRIPTION OF SYMBOLS 1... Video signal input terminal, 2... Vertical synchronization signal separation circuit, 6... Control head, 21... Trapezoidal wave generation circuit, 22... Phase comparison circuit, 25... Capstan motor, 28... Sample pulse generation circuit, 3
1... Oscillation circuit (counter), 32... Flip-flop, 33... AND gate, 34... Control pulse generation circuit, 35... Inverter, 40... Tracking monomulti, SW ₁ , SW ₂ ... Switch.

Claims (1)

[Claims] 1. When obtaining the trapezoidal wave signal necessary for the capstan servo, a 30 Hz signal is used that has passed through a tracking mono multi equipped with a tracking volume in a mode that requires adjustment of tracking deviation, while a In the capstan servo circuit of a magnetic recording/reproducing device that has a tracking adjustment circuit that is switched to use a 30Hz signal that does not pass through the tracking monomulti in the non-tracking mode, a signal with a frequency higher than the vertical synchronization signal separated from the video signal is A counter that counts signals and is reset by the vertical synchronization signal during recording, runs freely and outputs 60Hz oscillation output during playback, and the polarity is reversed when the count value of the counter reaches the threshold value.
Obtain a 30Hz output circuit that outputs a 30Hz signal, a 60Hz signal that has a timing different from the 30Hz timing, and create a 30Hz signal by calculating the logic between this 60Hz signal and the output signal of the 30Hz output circuit. A capstan for a magnetic recording and reproducing device, characterized in that the output obtained by calculating the logic is supplied to the circuit for obtaining control pulses, and the output is supplied to the tracking adjustment circuit. servo circuit.